Math 1310 Class Notes – Section 3.2, Page 1 of 9 Math 1310 Section 3.2 Functions and Graphs You can answer many questions given a graph. The graph of a function ( ) f x is the set of points ( x , y ) whose x coordinates are in the domain of f and whose y coordinates are are given by ( ). y f x = • Vertical line test First, does the graph represent a function? To answer this, you will need to use the vertical line test (VLT) . The Vertical Line Test: A graph in the xy plane is the graph of a function if and only if no vertical line intersects the graph more than one time.